Some fires have already been reported due to the earthquake damage. This video shows people outside after early warning alarms went off. The earthquake strikes about ~20 seconds into the video, when you can hear windows cracking and shaking of the building:

Now, it is unclear what the casualties might be, but it looks like significant damage has happened in Mexico City. People have been tweeting video from building in Mexico City showing billowing clouds of dust or smoke that could be from damaged buildings.

Now, it is way too early to say that this earthquake was triggered by the M8.1 that occurred earlier in the month. There could be the chance that the previous earthquake added more stress to a fault that was close to rupture. However, it will take time to determine if this was actually the case. Check out some of the discussion of triggering earthquakes on this USGS page.

Shockingly enough, today is the 32nd anniversary of the disastrous 1985 M8 earthquake that was centered about as far from the city as this one was today. Just hours earlier, people had participated in earthquake drills in memory of that earthquake, which killed at least 5,000 people.

I’ll update this post as new information comes in, but as with many large earthquakes, the region should expect aftershocks.

UPDATE: this video of an amusement park near Mexico City show how surface waves translated into water waves and just how much shaking there was.

UPDATE: Initial analysis of the earthquake seem to indicate that it was potentially caused by the same process that caused the M8.1 earlier in the month. The oceanic plate slab diving underneath Mexico appears to have “cracked”, causing an extensional earthquake.

Is this the Pacific Big Rip? Starts in Mexico, travels north though the San Andreas to Cascadia, then pummels the Aleutians. Toss in Oklahoma and Yellowstone for decoration. Beware total eclipses re the Allais Effect.

Michael Ross

Take your blooming pseudoscience elsewhere. Especially at a time like this. Despicable!

Erik Bosma

As in NW America and NE America? And then later we have SW America and SE America. Understand it’s quite Chile down in SW America this time of year.

Lorie Franceschi

At least 100 people dead and you think it is funny to make stupid comments. You sound like the south end of a north bound donkey

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Rocky Planet covers all the geologic events that made and will continue to shape our planet. From volcanoes to earthquakes to gold to oceans to other solar systems, I discuss what is intriguing and illuminating about the rocks beneath our feet and above our heads. Ever wonder what volcanoes are erupting? How tsunamis form and where? What rocks can tell us about ancient environments? How the Earth might change in the future? You'll find these answers and more on Rocky Planet.